1. Field of the Invention
The exemplary embodiment(s) of the present invention relates to an image capturing device and a control method thereof. More specifically, the exemplary embodiment(s) of the present invention relates to an image capturing device and an image capturing method thereof which increases image quality.
2. Description of the Related Art
In order to prevent the poor quality of image caused by camera shake while capturing, the manner of integrating multiple sampling images is applied in the digital camera for improvement of image quality. In the manner, shutter time must be shortened for a desired scene to capture a series of images, and a reference image is thereby selected among them. With respect to other captured images and the selected reference image, geometric moving measurement is executed to get a geometric conversion parameter between each of the images and the reference image. According to the given conversion parameter, each image is converted to make each image combine the selected reference image by point to point. Then, with some composition techniques, relevant image points distributed over all images are composited into a combined image which may be clearer than the original images.
With the principle of image capturing device, when the shutter time is decreased, the time of the camera shake or object moving in a particular scene is shorter than long time sampling, so that the resulted motion blur effect may be reduced. In the implementation, upon the initial detection result of exposure time, the exposure time is divided into multiple equal and smaller image sampling times, and a light sensor device captures multiple high frequently sampling images based upon its assigned image sampling time. Therefore, all of the high frequently sampling images have same light intensity, and the total image sampling time is equal to the preset exposure time of the image capturing device. In that manner, the exposure time of each processed frame is smaller than that of a correct exposure frame, and the accuracy estimated for motion information and the capability of motion blur compensation are improved.
However, in the motion frame, despite smaller sampling time that may reduce the motion measurement error, each of the high frequently sampling images is not analyzed for its effectiveness. When the blur caused by the motion frames is eliminated by the high sampling frequency, a pixel quantization error happens to the frame owing to the high sampling frequency, which does not make the image capturing device effectively increase the output image quality. Such a pixel quantization error is obviously more serious especially when the sampling frequency rises. With the repeated sampling and in consideration of sampling time shortening and the caused quantization error, the image quality improvement is a key.
Besides, the initial exposure time setting also limits the effect of composition of the high sampling frequency image to some extent. Thus, for the demand, designing an image capturing device and its image capturing method thereof to increases image quality has become an urgent issue for the market application.